Power Factor Calculator

Calculate power factor and reactive power for AC circuits.

Real Power (W)

Apparent Power (VA)

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Guides & Reference

How It Works

PF = Real Power (W) / Apparent Power (VA). PF of 1.0 = perfect efficiency. Industrial facilities penalized for PF below 0.85.

Formula

PF = P / S

Common calculations — results you can verify instantly.

800W, 1000VA

800/1000

PF=0.80

Perfect PF

W equals VA

PF=1.0

Industrial standard

Minimum acceptable

PF > 0.85

✓

Capacitors correct low power factor from inductive loads.

✓

Residential utilities do not penalize power factor.

Confusing watts with volt-amperes

W = real power. VA = apparent power. PF = W/VA.

Ignoring PF for residential

Power factor penalties apply to commercial and industrial billing.

Inductive loads: motors, transformers, fluorescent ballasts.

Install power factor correction capacitors.

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